The invention relates to optical detector systems having a universal type dual port, dual lense, optic module usable in both through-beam and retroreflective systems.
In a retro-reflective system, FIG. 1, a transmitter module has two ports, each with a focusing lense. Infra-red light or the like is emitted from one port towards a reflector, and received at the other port to complete an optical circuit and trigger the appropriate detection circuitry. An object moving through the optical path interrupts the circuit, which absence of light is detected at the receiving port and appropriately interpreted by the detection circuitry for performing a given function, such as closing or opening a switch, counting, verification, etc.
In a through-beam optical detector system, FIG. 2, the receiver is separate, and remotely spaced from the transmitter. Light emitted from the transmitter travels directly to the receiver, without reflection.
For cost efficiency, including tooling expense, the dual port optic housing module of the retro-reflective system is commonly used in the through-beam system. Only one port of the housing module is used for transmitting light, while the other port is an unused dummy. A second module, which may also be a dual port type, is used for housing the receiver. One port has the photo-receiving circuitry, while the other port is an unused dummy. This arrangement is known in the art, and enables universal use of the dual port optic housing module.
The present invention provides an improvement in the through-beam system. An auxiliary light source is provided in the available but unused port of the transmitter module for transmitting visible light to aid alignment of the transmitter and the receiver.